The present invention deals with the problems of misalignment in interferometers, particularly misalignment due to temperature changes. Serious functional problems occur in interferometers if, in spite of initial careful alignment, events occur which cause the alignment accuracy to be lost.
Problems of this type have been persistent difficulties in the interferometer field. The present applicant has tried various concepts in an effort to solve misalignment problems, and thus improve interferometer performance. Diagnoses of the causes of the problems have been highly speculative, and lacking in conceptual absolutes. However, the concepts herein disclosed appear to provide major benefits, substantially reducing misalignment problems, and thereby improving interferometer performance to an extent which may constitute an order of magnitude.